Paging Tootsie: Below-the-knee skirts, bow blouses, and pearls may be forever coming back into vogue, but that doesn't mean you should put them all together. "When you wear pieces exactly like they were worn the first time around, it's as if you've been stuck in a look," says Lloyd Boston, a stylist in New York City and Los Angeles and the author of "The Style Checklist."

The more youthful approach: "The classics can be refreshed when you style them differently," says Boston. Pair that secretary blouse with jeans, tuck a long-sleeve tee into a calf-length skirt and add a cashmere scarf, or layer pearls with a mix of chains in different lengths.

You know the one: that leather workhorse with a nondescript buckle that's not too wide and not too thin. Remember: A belt should be an accent, not serve a function. If you need one to hold up your pants, it's time to visit the tailor, says Lauren A. Rothman, the founder of the Washington, D.C.-based fashion-consulting firm Styleauteur.com.

The more youthful approach: Stock up on a kaleidoscope of thick and skinny belts to liven up the outfits in your closet. Trousers or dark jeans work well with a thin belt in a contrasting color. Wide belts are great for cinching dresses, jackets, and cardigans; if they're dark-colored, they can even make your waist look smaller. If you can invest in only one, opt for a slim belt in a shimmery metallic, brown leather, or an animal print, so it goes with everything.

Whether or not you like your neck, tying a silk scarf stewardess-style or draping it over one shoulder is an instant-ager -- even if the thing cost as much as your iPad. "The silk scarf can be a fashion fossil," says Rothman.

The more youthful approach: "The coolest scarves are made of an ethereal, lightweight knit, are long enough to be wrapped around several times, and come in unexpected colors and prints," says Boston. Florals and geometrics tend to look most current, but "paisley, equestrian, and sailor themes can add years," says Boston. However, you don't have to ditch all your silk squares. What's most important is how you wear them. You can roll the scarf up and use it as a headband or tie it to the handle of a purse. Or try it "backwards," in place of a necklace: Fold a large square scarf into a triangle. Tie the ends around the back of your neck with the "tail" positioned in the front -- picture John Wayne -- leaving several inches of drop space around your neckline for the fabric to drape. (Watch this video for the easy how-tos.)

Tan pants, a cream shirt, brown shoes and you're out the door, right? Yawn. There's a fine line between creating a signature classic look and getting stuck in the fuddy-duddy zone.

The more youthful approach: That same neutral palette can ooze style if you choose pieces with interesting details and shapes instead of cookie-cutter basics. Alternatively, stick with a simple outfit but inject a dose of fun with a boldly colored jacket or metallic flats. "Take chances -- style begins where the rules end," says Boston.

Granted, no one enjoys suffering through stilettos, but footwear with thick rubber soles or wide, squarish toe boxes can frumpify even the chicest of ensembles.

The more youthful approach: Keep feet happy with wedges (which balance weight along the entire foot), pumps with comfort features (Cole Haan and Kenneth Cole offer these), or flats with built-in arches and sturdy construction. (To test the comfort level of flats, hold the toe and heel areas and try to twist the shoe. If the sole twists halfway around, it most likely won't give you the support that you need.) And when opting for a pointy-toed style, "make sure to go half a size larger for more toe room," recommends Rothman.

What's Aging You: Underperforming Undies

Visible panty lines make for a lumpy rear, and an unsupportive bra can drag you down. A dead giveaway that yours isn't holding up: The band rides up in the back above your shoulder blades, so your breasts drop in front.

The more youthful approach: First, get a better bra. Before you try one on, check the profile of the cups -- they should slant upward, not downward like teardrops. In the dressing room, make sure the band sits level from front to back and fits snugly (meaning you should be able to comfortably slide only one finger underneath it). As for those pesky panty lines, banish them by selecting a bottom with laser-cut edges. For more heavy-duty smoothing, try shapewear: "It helps you feel more in control and makes clothing fit better," says Charla Krupp, the author of "How Not to Look Old." Find a body shaper that doesn't create a muffin top or an unsightly bulge where the garment ends. Krupp's pick: high-waisted bike shorts.

It's natural to feel an affinity for onetime fashion favorites, like twinsets, nude hose, and mock turtlenecks. "When women hang on to what they perceive as a winning look, they get caught wearing something that's expired," says Boston.

The more youthful approach: Alas, some items need to be sent to the big fashion heaven in the sky. The mock turtleneck has given way to the regular turtleneck; mules have been swapped for flats. And since nude nylons make even the dewy-faced Duchess of Cambridge (née Kate Middleton) look mumsy, stick with opaque or textured tights or bare legs (use self-tanner on pasty gams). You can salvage the twinset by wearing each piece separately.

What's Aging You: Boxy Cuts

So what if your 22-year-old body is long gone? That's no reason to hide under muumuu-esque tunics, manly suits, or those pajama-like linen separates. "The older you get, the more important it is to have properly fitting clothes," says Kim Johnson Gross, the author of "What to Wear for the Rest of Your Life."

The more youthful approach: Well-tailored or draped garments -- e.g., a structured jacket with a nipped waist or a ruched jersey dress -- hint at your figure while camouflaging the parts that you're not so crazy about. "No matter your size, formfitting clothes make you look younger, because you're showing that you have a bust, a waist, and hips," says Krupp.

What's Aging You: Same Bag, All the Time

Schlepping a heavy black satchel, no matter what, even if it's the middle of July or you're at a fancy affair, says that you're set in your ways and unwilling to change with the times. "It's an easy mistake, since your bag becomes such an extension of you that you almost forget that it's there," says Boston.

The more youthful approach: Don't blow your budget on an enormous bag collection. "You need only one day bag each for warm and cool months," says Krupp. For May through August, opt for bright or pale shades in leather, suede, or straw. Come fall, try gray or an animal print. If you want just one year-round option, go with a jewel tone. For parties, choose a metallic clutch that coordinates with anything.

No one ever sets out to be mutton dressed as lamb. Nonetheless, trying too hard to be hip -- think four-inch strappy platforms and leather leggings -- can make you look older by comparison. For reference, see The Real Housewives of Everywhere.

The more youthful approach: You don't have to sit out on every hot trend. Many brands (Ann Taylor, Banana Republic, DKNY) offer grown-up versions of the latest styles. Instead of teenybopper leggings, buy a pair in a high-quality knit and wear them with a long tunic. When miniskirts are in, find a middle ground with a hemline that goes only two or three inches above the knee. "You know a trendy item is age-appropriate if it easily fits in with the rest of your wardrobe," says Boston. The piece should also be available in the stores and departments that you're used to shopping in. "When a 15-year-old is wearing it, chances are you shouldn't be," says Rothman.

What's Aging You: Too Much Razzle-Dazzle

True, sparkly stuff has been all the rage lately. But when you go overboard with metallics, sequins, and other bedazzlements, Peg Bundy-style, your clothes suggest that you're more interested in guarding your slot machine in Atlantic City than you are in staying on trend.

The more youthful approach: The key to looking your best as you age is to aim for elegance. Burn those rhinestone-pocketed jeans and incorporate shimmer in a subtle, sophisticated way: Try a blouse with beading the same color as the fabric, a gemstone-collared sheath, or a sequin-trimmed cardigan. "Less is more," says Sherrie Mathieson, the author of "Steal This Style."

What's Aging You: Underaccessorizing

You put on a top, a bottom, and shoes, and consider your ensemble complete. But as Olympia Dukakis's character wisely said in "Steel Magnolias": "The only thing that separates us from the animals is our ability to accessorize." Seriously, though, if you're not putting a little extra effort into getting dressed, you'll create the impression that your style has stopped evolving and you've given up on the idea that fashion is fun.

The more youthful approach: Finishing touches, such as jewelry, a scarf, and a belt, are critical. Start with baby steps. "Try never to leave the house without a piece of statement jewelry," says Rothman. "A versatile yet modern style is a long necklace of circular links in gold or silver." Boston suggests these items for no-brainer outfit completion: a silver cuff, a conversation-starting cocktail ring, and chandelier earrings.

They're the office version of mom jeans, with a pleated front and a high waist. "These pants are from a time when there weren't a lot of business-casual options for women," says Rothman. Due to the extra coverage, some women mistakenly feel that this style helps hide a pooch, yet the cut actually magnifies problem areas.

The more youthful approach: You'll look younger, not to mention slimmer, in flat-front, midrise trousers with a straight or boot cut. "An inch under your navel is universally flattering," says Mathieson. "The pants should barely hug your thighs and gradually get a little wider toward the hem to balance out your upper body."

What's Aging You: Wide-Leg Cropped Pants

These flares "hit you at the worst possible spot between the knee and the ankle, shortening legs and adding bulk," says Krupp. Even Heidi Klum's limbs would look like tree trunks in these.

The more youthful approach: Channel Audrey Hepburn with slim-cut Capris that are as sleek as possible. (Really, would the Funny Face star have been seen in anything with cargo pockets?) Keep your body type in mind: Curvy figures benefit from a straighter leg, while slender frames can pull off pegged cuffs. Five inches above the ankle is a flattering length for most women.

What's Aging You: Certain Pastels

If you're not careful, these soft and sweet shades end up reading girlie or Golden Girls-y -- neither of which is the goal.

The more youthful approach: Jewel tones are a safer bet. They look modern and tend to flatter multiple complexions, hair colors, and ages, says Boston. However, you don't have to rule out pastels, especially since they're a big trend this spring. It's about wearing them in a cooler way. Pair them with subdued neutrals -- try mint green with either gray (in the winter) or white (in the summer). "This looks fresh and makes the pastels pop," says Rothman. Another good idea: Choose a streamlined garment, like a Jackie O.-inspired shift, instead of something with fussy ruffles.

What's Aging You: Workout Clothes When You're Not Working Out

There's a time for fleece jackets, white cross-trainers, and oversize tees -- and it's when you're on the treadmill or repainting the den, not when you're doing activities that don't make you break a sweat.

The more youthful approach: Thanks to long jersey tops, knit dresses, stretch jeans, and leggings, you can be comfortable without resembling a mall walker. However, if you want to be able to shoot straight from Pilates to lunch with the girls, go with workout gear from style-savvy brands like Lululemon and Beyond Yoga. And always apply the same rules that you would to any outfit, says Rothman: Colors (including shades of black) should match; clothes shouldn't be dingy or beat up; and cuts should flatter your body (ditch the XXL college T-shirts, boxy zip-ups, and awkwardly short yoga pants). Another thing: All-white sneakers can have an orthopedic look, so choose a pair with color.

What's Aging You: Matchy-Matchy Jewelry

Sure, the heart pendant, bracelet, and earrings were sold as a set, but should they all be worn at the same time? "That totally dates you," says Gross.

The more youthful approach: Go for contrasting yet complementary baubles. "You want to be a little 'off,' so that people wonder, Where did she get that?" says Krupp. Let one item be the focal point (such as a bib necklace or oversize gemstone drops), then base others around it -- don't force bold pieces to compete. And despite what Mom might have told you, it's perfectly fine to mix silver and gold, particularly if the pieces are worn next to one another, like stacked necklaces or bangles.